Remove getrandom dependency from csr_rust

[Balint Molnar]

Problem Statement

getrandom dependency is needed for csr_rust module to be able to compile it to target wasm-unknown-unknown. It triples the compiled wasm module size, so we should investigate if we can drop this.

Proposed Solution

Drop this dependency and try to compile the module without it to make the wasm module more compact.

[Balint Molnar]

It was fixed with #15